The Fire Marshal says he has the point of origin narrowed down to a ten-foot radius but has not yet found the cause.
iPad video taken by Action News viewer Shawn McClellan show the Magic Cottage School going up in flames.
"Flames pouring out, and then it seemed like they had it under control, and they would get down off of the roof and it would start up again," he said.
The blaze at the Appletree Drive school was stubborn and burned for more than 40 minutes after it began just after 2:00 p.m Saturday.
More than 50 firefighters responded to the fire they believe began in a classroom being used for storage.
"We opened up the roof for ventilation," said Levittown Fire Chief Ralph Gumbert. "The fire had been trapped in between layers of the roof that had styrofoam in it.
McClellan's iPad video caught the commotion after crews working to get water from a hydrant hit a setback. The hydrant exploded out of the ground, injuring a firefighter in the leg.
Another firefighter was injured in the shoulder while working inside the school.
Crews had the fire under control within 40 minutes.
The owners say there is extensive damage, including flooding. The 50 or so students enrolled will still have school on Monday, but at a different location.
"We're still open. However our Yardley location will be taking the children next week. We want to get all the smoke out. You know, we want everything to be clear for the children," said owner Andrea Vreeswyk.
Both injured firefighters were transported to the hospital. Action News is told the injuries are not life-threatening. Both were expected to be treated and released by Saturday night.